Field of the Invention
The present invention relates to a step-down chopper circuit, and more particularly, it relates to a step-down chopper circuit including a switching device circuit and a backflow prevention diode circuit.
Description of the Background Art
A step-down chopper circuit including a switching device circuit and a backflow prevention diode circuit is known in general, as disclosed in Japanese Patent Laying-Open No. 2010-239770.
Japanese Patent Laying-Open No. 2010-239770 discloses a DC-DC converter including switches and diodes that prevent current backflow. This DC-DC converter is configured to step down the voltage of regeneration power from an electrical rotating machine (rotating electrical machine) and apply the stepped-down voltage to a power source. The DC-DC converter also includes capacitors and a control circuit, and the control circuit controls on and off periods (duty) of the switches to control the charge and discharge amounts of the capacitors and step down the voltages. The diodes are arranged to prevent current backflow to the electrical rotating machine. Furthermore, in general, in this DC-DC converter, the switches and the diodes that prevent current backflow are housed in the same package.
However, in the conventional structure in which the switches (switching device circuit) and the diodes (backflow prevention diode circuit) that prevent current backflow are housed in the same package, the whole package is replaced even when one of the switching device circuit and the backflow prevention diode circuit fails. Thus, not only the failing device but also the device that is not failing is disadvantageously replaced. Therefore, in the DC-DC converter (step-down chopper circuit) described in Japanese Patent Laying-Open No. 2010-239770, the switching device circuit or the backflow prevention diode circuit that requires no replacement is disadvantageously replaced.